The objective of this work was to characterize the Gulf of California "summer" upwelling effect on the spatial distribution of surface chlorophyll α concentration (Chl sat) and T °C (SST) with satellite data. Weekly composites of SST data from the sensor AVIlRR imagery (NOAA-9 satellite), and daily Chl sat, imagery from the sensor CZCS (Nimbus-7 satellite) were used to generate graphs with the spatial distribution of these variables for the Gulf of California region to the south of the midriff islands. The Gulf of California summer upwelling has an appreciable effect on the horizontal distribution of SST and Chl sat but itis very weak. This is mainly due or a very strong water column stratification, with surface temperatures up to >31 °C, which greatly decrease vertical water transport near the Baja California coast. SST has a general tendency to increase from Baja California to the eastern coast, with a weak gradient of one to two degrees through the whole Gulf (from 29 °C off Baja California to 31°C off the eastern coast). Chl sat shows an inverse gradient, with higher values off the western coast (up to 0.2 mg m3) and decreasing to <0.1 mg m3off the eastern coast. In some cases there were very clear plumes and eddies, such as the cyclonic eddies observed on the SST distribution, with core values of 28 °C A Chl sat plume with relatively high values (-0.2 mgm3) indicated advection from Baja California towards Sonora in the northern part of our study are
